This invention concerns siding for a house or other frame structure, and is more particularly concerned with an improved clapboard siding which is resistant to wind and rain and which is structured to avoid moisture and heat buildup in the siding and in the space just beneath the siding.
Clapboard siding, per se, is a well known term in the building trades, as its form and the manner of applying it to houses or other structures have not changed significantly for over a century. "Bevel siding" is another commonly used term for clapboards.
The name "clapboard" is derived from the clapping noise created when a number of the boards are carried on a shoulder at one time. Clapboards were one of the first items exported to the old world by the early settlers of the New England Colonies. The original use of clapboards as siding was on "half timber" or "post and beam" type buildings which had used "wattle and daub" or brick to fill in spaces between the exposed timber framing. Through the years the art of building was changed to using studs and corner bracing and a plywood or composite board subsiding, while still covering the exterior with clapboards. The use of clapboards by the early settlers, as now, was to shed rain as well as sunlight, while beautifying. Stopping wind and insulating was a function of the wattle and daub, and these are functions of the subsiding and insulation today. Thus, clapboards function more as shedders of sun and rain, not as wind and heat barriers.
Wind blowing over a structure creates a negative pressure on the lee side, causing warm, moist air to be drawn out of the building on the lee side. However, conventional clapboards restrict this moisture from leaving the structure. Accordingly, holes are then bored through the siding to inlets and outlets for air and vapor.
Sunlight raises the exterior surface temperature of the building as high as 170.degree. F. Clapboard and other wood sidings will hold five to ten times more water at this high temperature than they hold at normal air temperatures. When the temperature drops, the moisture condenses, often blistering the paint or finish on the siding, and often leading to rot and warping. Moisture, mold and mildew problems within many houses are often caused by wide temperature variations within the envelope of the building.
Conventional clapboard siding also tends to pick up rainwater and to "wick" the rain up into the lap between adjacent clapboards. This is especially true on the windward side of the house or other structure. This water adds to the problem of moisture mentioned previously.